Multifold balloon for stent deployment

Abstract

The present invention utilizes a balloon with three or more folds to more evenly distribute the frictional forces on the inside of a stent during stent deployment thus improving the uniformity of stent cell expansion. Ideally one would like to have the same number of balloon folds as the number of stent cells distributed circumferentially around the stent. Matching the number of balloon folds to the number of cells of each cylindrical segment of the stent provides better size uniformity for the stent cells after they are expanded against the wall or other vessel within a human body.

What is claimed is: 
     
       1. A balloon angioplasty catheter having a distal section and having an inflatable multifold balloon situated at the catheter's distal section, the multifold balloon having a thin wall formed from a plastic material, the balloon having at its longitudinal center at least three folds when in a compressed state prior to balloon inflation with each fold consisting of folding of the balloon's thin wall first in one direction and then the opposite direction so that each one of the at least three folds consists of three layers of the thin wall of the balloon. 
     
     
       2. The catheter of claim 1 wherein the balloon angioplasty catheter has a central lumen throughout its entire length, the balloon angioplasty catheter being of the "over-the-wire" design. 
     
     
       3. The catheter of claim 1 wherein the balloon angioplasty catheter has a distal half-length, the balloon angioplasty catheter being a "rapid exchange" design characterized by having an entry port for a guide wire situated within the distal half-length of the balloon angioplasty catheter. 
     
     
       4. A multifold balloon stent delivery catheter comprising; a balloon angioplasty catheter having a distal section and having an inflatable multifold balloon situated at the catheter's distal section, the multifold balloon having a thin wall formed from a plastic material, the balloon having at its longitudinal center at least three folds when in a compressed state prior to balloon inflation with each fold consisting of folding of the balloon's thin wall first in one direction and then the opposite direction so that each one of the at least three folds consists of three layers of the thin wall of the balloon; and,   a stent placed onto the multifold balloon of the balloon angioplasty catheter, the stent having a multiplicity of cylindrical segments each cylindrical segment consisting of a number of stent cells and the stent further consisting of at least three stent cells circumferentially disposed within each cylindrical segment.   
     
     
       5. The stent delivery catheter of claim 4 wherein the balloon angioplasty catheter has a central lumen throughout its entire length, the balloon angioplasty catheter being of the "over-the-wire" design. 
     
     
       6. The stent delivery catheter of claim 4 wherein the balloon angioplasty catheter has a distal half-length, the balloon angioplasty catheter being a "rapid exchange" design characterized by having an entry port for a guide wire situated within the distal half-length of the balloon angioplasty catheter. 
     
     
       7. The stent delivery catheter of claim 4 including a sheath which covers the stent during catheter introduction into the body, the sheath being adapted to be moved proximally to uncover the stent for stent deployment by balloon expansion. 
     
     
       8. The stent delivery catheter of claim 4 wherein the number of folds of the angioplasty balloon is twice the number of stent cells within one cylindrical segment around the circumference of the stent. 
     
     
       9. The stent delivery catheter of claim 4 wherein the number of folds of the angioplasty balloon is exactly half the number of stent cells within one cylindrical segment around the circumference of the stent. 
     
     
       10. The stent delivery catheter of claim 4 wherein the number of folds of the angioplasty balloon is the same as the number of cells within each cylindrical segment of the stent. 
     
     
       11. The stent delivery catheter of claim 10 wherein there are exactly five folds of the balloon and the stent has exactly five cells circumferentially disposed around each cylindrical segment of the stent. 
     
     
       12. The stent delivery catheter of claim 10 wherein there are exactly six folds of the balloon and the stent has exactly six cells circumferentially disposed around each cylindrical segment of the stent. 
     
     
       13. The stent delivery catheter of claim 10 wherein there are exactly seven folds of the balloon and the stent has exactly seven cells circumferentially disposed around each cylindrical segment of the stent. 
     
     
       14. The stent delivery catheter of claim 10 wherein there are exactly eight folds of the balloon and the stent has exactly eight cells circumferentially disposed around each cylindrical segment of the stent. 
     
     
       15. The stent delivery catheter of claim 10 wherein there are exactly nine folds of the balloon and the stent has exactly nine cells circumferentially disposed around each cylindrical segment of the stent.